CCC-0721 GRTUNCL3D.

1. NAME OR DESIGNATION OF PROGRAM:  GRTUNCL3D

3. DESCRIPTION OF PROGRAM OR FUNCTION

The code GRTUNCL (distributed within the CCC-0650/DOORS package) has been used for years to generate uncollided flux and first collision source distributions for the two-dimensional discrete ordinates transport code DORT. GRTUNCL3D was written to perform this same function for the three-dimensional discrete ordinates transport code TORT. Although TORT can perform three-dimensional calculations in both rectilinear X, Y, Z and curvilinear R, Q, Z geometries, the current initial version of GRTUNCL3D is only operational in X, Y, Z cartesian geometries. However, since TORT has the ability to perform calculations on a multilevel discontinuous mesh, i.e., geometries containing a different number of cells in each row and a different number of rows in each plane, GRTUNCL3D was written to generate uncollided flux and first collision source distributions for X, Y, Z discontinuous space meshes. In addition, it employs a simple scheme of cell subdivision which can provide improved estimates of the average uncollided flux and first collision source within each cell; it performs a system balance calculation to aid the user in determining whether or not the fine mesh is sufficient to yield credible results; it dynamically allocates all memory as needed; and finally, it obtains many of its control parameters and all of the geometry data from the TORT input file thereby eliminating any duplication of input data.

4. METHODS

The semi-analytic first collision source technique employed by GRTUNCL3D consists of estimating the average uncollided flux within each TORT fine mesh cell and then folding these uncollided fluxes with angular scattering data to obtain first collision source moments. The estimate of the average uncollided flux within each cell is obtained by performing a 'ray trace' calculation between each of the source points and each fine mesh cell center to determine the number of mean-free-paths along the source-cell center 'ray'.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The current version of GRTUNCL3D is only operational in x,y,z Cartesian geometries. It is not intended for use in curvilinear geometries, i.e., spherical or cylindrical geometries. In addition, it cannot treat geometries with reflected and/or periodic boundaries unless all source points are common to one or more of these boundaries.  In geometries with one, two, or three reflected and/or periodic boundaries, all source points must lie on or very close to the reflected or periodic boundary, the edge common to the two reflected or periodic boundaries, or the corner common to all three reflected or periodic boundaries, respectively.

6. TYPICAL RUNNING TIME

The test case ran in ~2 minutes on a Pentium 4 1.4GHz under Windows 2000.

10. REFERENCES

Background information:
- R. A. Lillie, 'GRTUNCL3D: A Discontinuous Mesh Three-Dimensional First Collision Source Code,'  Proc. Am. Nucl. Soc. RP&S Div. Top. Conf., Vol I, pp 368-375, Nashville, TN, (Apr.19-23, 1998).
- W. A. Rhoades and D. B. Simpson, 'The TORT Three-Dimensional Discrete Ordinates Neutron/Photon Transport Code,' ORNL/TM-13221 (October 1997).
- R. L. Childs, 'GRTUNCL: First Collision Source Program,' ORNL Informal Notes (1982).

- J. O. Johnson (Ed.):
GRTUNCL3D excerpt from 'A User's Manual for Mash 1.0 - A Monte Carlo Adjoint
Shielding Code System,' ORNL/TM-11778 (March 1992)

11. HARDWARE REQUIREMENTS

GRTUNCL3D was developed on IBM RS/6000 workstations and has been ported to personal computers running Linux and Windows.

13. SOFTWARE REQUIREMENTS

GRTUNC3D runs under AIX, Linux and Windows operating systems. Executables created with Portland Group, Inc. compilers are included both for Linux and Windows. All other systems require Fortran and C compilers. GRTUNCL3D was tested on the following systems:
  
IBM RS/6000 on AIX 4.3.3 with IBM XL Fortran for AIX Version 08.01.0000.0000
IBM RS/6000 on AIX 5.1 with IBM XL Fortran for AIX Version 08.01.0000.0003
AMD Athlon on RedHat Linux 7.3 with Portland Group, Inc.Fortran 4.0 2 & GNU gcc 2.96
PC on Windows 2000 with Portland Group, Inc. Fortran.4.0 2 and PGI C 4.0 2
PC on Windows XP with the included PGI executable created under Windows 2000
  
The Windows executable can be run in a command prompt window (of WindowsXP or Windows2000) in a manner similar to UNIX executables (uses redirection for input and output.) The test case requires that GIP and TORT be running on the same computer. These modules are not included in this distribution but are available in the CCC-650/DOORS3.2a package available from RSICC.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

WinZIP 8.0 or newer is required to expand the distribution file under Windows.

15. NAME AND ESTABLISHMENT OF AUTHORS

Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, USA
Developed by:   Oak Ridge National Laboratory
                Oak Ridge, Tennessee, USA

Readme.txt  Readme file
ccc.c       the C routines required by grtunc3d on IBM AIX and PC Linux
ccc-win.c   the C routines required by grtunc3d on PC Windows
libtort.f   fortran routines from the DOORS subroutine library required by
grtunc3d
grtunc3d.f  grtunc3d fortran deck
gugip.inp   input to gip required to make cross-section file for grtunc3d sample

problem
gex.inp     grtunc3d sample problem input file
tex.inp     tort input file required to run grtunc3d sample problem
bin\linux\grtunc3d   PGI compiled executable for Linux
bin\windows\grtunc3d.exe   PGI compiled executable for Windows
out         directory containing ORNL output files for comparison
Documentation